The LT4356 replaces complicated and bulky protection circuitry with a simple IC and FET solution. It provides a well-regulated output during an overvoltage transient, allowing continued operation through the event. Front-end protection permits the use of lower cost DC/DC regulators downstream. During an overvoltage event, the LT4356 regulates the output to a user-defined voltage by controlling the gate of an external N-Channel MOSFET. Inrush current limiting is achieved by controlling the voltage slew rate of the gate. The LT4356 monitors voltage drop across a current sense resistor at the input of the circuit to protect against overcurrent faults. For either an overvoltage or overcurrent fault condition, an integrated fault timer ensures safe shutdown of the MOSFET if the fault persists.
An auxiliary amplifier is provided for additional design flexibility. It may be used as a voltage detection comparator or a low drop out (LDO) linear regulator controller. The LT4356 is available in two options defined by the function of the shutdown pin. For the LT4356-1, shutdown of the IC reduces the quiescent current to 5uA. For the LT4356-2, the auxiliary amplifier and internal reference remain active to ensure a keep-alive supply voltage for vital functions while the main system is shutdown. Quiescent current is reduced to 50uA during shutdown.
Specified over the full commercial, industrial and automotive temperature ranges, the LT4356 is offered in (4mm x 3mm) 12-pin DFN and 10-pin MSOP packages. Evaluation kits are available from the factory. Pricing begins at $1.98 each for 1,000-piece quantities and the device is available today in production quantities.